Integrated circuits have been developed into complex devices capable of including millions of transistors, capacitors and resistors on one chip. In accordance with development of chip designs, faster electric network and higher circuit density have been continually required.
The requirement for faster circuits having higher circuit densities has been directly reflected in materials used to fabricate such integrated circuits.
As size of patterns become decreased in accordance with miniaturization and integration of semiconductor devices, thickness of a photoresist film and thickness of the patterns become thinner to prevent a collapse phenomenon of the photoresist patterns.
However, it is difficult to etch a layer to be etched by using thinner photoresist patterns.
That is, according to high integration of the semiconductor device, an aspect ratio of the photoresist patterns obtained by a lithography process is increased, such that capillary force between the photoresist patterns during a subsequent washing process is also increased, thereby causing a problem in that the photoresist patterns are collapsed.
When the thickness of the photoresist film is decreased to be 200 nm or less in order to solve the problem, an etch selectivity of the photoresist patterns to a lower layer to be etched during a subsequent etching process using the photoresist patterns as an etching mask may not be sufficiently secured, such that it is not possible to form uniform circuit patterns.
In addition, since a photoresist material appropriate for short wavelength light source includes an aliphatic compound rather than an aromatic compound such as benzene as a main component, it is significantly difficult to secure sufficient etching resistance. For example, at the time of etching the layer to be etched, etc., formed of an insulating layer such as silicon oxide (SiO2), deformation of the layer to be etched occurs, such that it is almost impossible to manufacture a semiconductor device.
Accordingly, in order to improve the disadvantage of difficulty in etching the layer which is etched by using thinner photoresist patterns, an inorganic or organic film material having strong etching resistance is introduced between the layer to be etched and the photoresist of a semiconductor substrate, wherein the film material is referred to as a hard mask.
In addition, a hard mask process means a process of etching the hard mask using the photoresist patterns to perform patterning, and etching the layer to be etched using the patterns of the hard mask.
In general, since the hard mask is capable of obtaining a sufficient selection ratio with respect to the lower layer even if the photoresist film has a thin thickness, the hard mask does not have limitation on coating thickness of the photoresist film to be formed.
However, the hard mask process not only requires a photoresist coating process and other separate deposition apparatuses, but also performs complex processes, such that there are problems in that deposition efficiency is low, throughput is decreased, and production cost is increased, etc.
Therefore, in order to simplify existing hard mask processes and to reduce the production cost, it is demanded to develop a hard mask composition capable of being formed by the same solution process as the photoresist coating process, and having excellent properties such as an excellent etch selectivity, etc., to the photoresist.